The present invention relates generally to gauges utilized to measure the internal gas pressure of a container and more particularly the invention relates to an apparatus and method for testing such gauges without depressurizing the container or damaging the gauge.
Portable gas containers serve a variety of uses, one of which is as a storage container for the so-called stored pressure fire extinguishers, which use a chemical agent propelled from the container by a stream of pressurized gas, such as nitrogen. Mounted on a number of such fire extinguishers is a pressure gauge which indicates the internal pressure, usually 50 to 300 psi. Routine maintenance of these devices requires that the container be periodically checked for proper pressurization. Clearly, then, if the gauge functions properly a simple visual inspection would indicate whether the proper pressurization exists. However, the certainty of the gauge accuracy is a subject of uncertainty in that the gauge may be defective, damaged, or simply stuck. Therefore, it has been common practice in the past to shake, thump, rattle, bump or otherwise attempt to coax some variation in the reading on the gauge in order to assure that the reading is not inaccurate.
Such gauges as hereinabove referred to measure the differential between the internal pressure of the container and the pressure within the cover of said gauge, which is preferably at atmospheric pressure. The pressure within the face cover is equalized to atmospheric pressure by perforations in the cover. Heretofore such perforations have been located in accordance with the gauge manufacturers' fancy. However, the concensus of such manufacturers is increasingly moving toward locating such perforations at the center of the face cover.